In November 2012, Colorado and Washington were the first states that passed referendums to legalize adult recreational marijuana use. Alaska and Oregon voters followed suit by supporting legalization of recreational marijuana in the 2014 elections. With a rapidly changing cultural and political landscape and growing public support of marijuana use, it is essential to quickly obtain information that will inform and prepare both patients and health providers in making decisions and promoting behaviors that reduce potential health risk associated with marijuana use. One area that has received little attention is the use of marijuana during pregnancy. Our prior work suggests that more women may be using marijuana during pregnancy than previously estimated and that the majority of these users are not currently telling their obstetric providers about this use. Several studies suggest that perinatal marijuana is associated with various negative pregnancy, infant and child outcomes including stillbirth, preterm delivery, neurocognitive deficits in infants and children, and behavioral, learning, and mental health problems among children and adolescents. To accelerate research on this topic and more expeditiously provide information to guide clinical practice and health system policies, this proposal intends to take advantage of rich, varied data collected from our parent study (NIDA 1R01DA026410). Our project has data from 469 pregnant patients and 81 obstetric providers recruited from 5 different obstetric practices in Pittsburgh, Pennsylvania. In this parent study, we found 29% of our pregnant patients either tested positive or admitted to current marijuana use during their first obstetric visit; however, only 36% of patients who tested positive for marijuana disclosed current use. Although our original study objectives did not specifically target marijuana, we were able to add questions in our data collection to both our surveys and semi-structured interviews that examined pregnant marijuana user's history of use, attitudes and beliefs regarding perinatal marijuana and obstetric care providers' attitudes, strategies, and concerns about addressing perinatal marijuana use. We will compare quantitative data from our patient participants who either disclosed or tested positive for marijuana use during pregnancy with those from patients who did not. We will analyze data from over 190 interviews to provide a deeper understanding of patients' and obstetric providers' perspectives on perinatal marijuana and what they perceive is needed to better address this in obstetric care. Findings from our study will inform future development of provider training interventions and patient information/counseling resources as well as clinical guidelines and health system policies.